Method for processing non-metallized groove hole at orifice end face of hole wall metallized orifice, circuit board

Abstract

The application discloses a processing method for a hole-wall metalized hole mouth end face non-metalized slot hole and a circuit board. The processing method comprises the following steps: S1, manufacturing an operation board with two groups of circuit structures and a slot hole sketch, a connecting copper layer extending to outer layer circuit layers of the two groups of circuit structures is arranged on an inner wall of the slot hole sketch, and a part of the connecting copper layer on the two outer layer circuit layers is a to-be-removed part; S2, when a protective tin layer is arranged on surfaces of the outer layer circuit layers and the connecting copper layer, the following S3 is performed; otherwise, the protective tin layer is arranged on the surfaces of the outer layer circuit layers and the connecting copper layer; S3, removing the protective tin layer on a set region of the to-be-removed part to form a processing window; etching away the to-be-removed part based on the processing window; and S4, peeling off the protective tin layer to manufacture the slot hole with a hole-wall metalized hole mouth end face non-metalized. The processing method can accurately manufacture the slot hole, the circuit board has excellent shielding effect, and the sensitivity and stability of an ultrasonic sensor are ensured.

Description

Technical Field

[0001] This invention relates to the field of circuit board technology, and in particular to a method for processing slots with metallized hole walls and non-metallized end faces, and a circuit board thereof. Background Technology

[0002] Currently, during the assembly and / or installation of ultrasonic sensors, the slots on the sensor's circuit board need to be fitted with internal components (such as damping components, seals, etc.) or external components (such as liquid or gas channels). However, considering factors such as signal shielding effectiveness, the stability of the overall sensor structure, and the mounting conditions between the circuit board and the chip, the slots on the circuit board need to be specially designed to have the structural characteristics of "metallized hole walls and non-metallized hole openings".

[0003] However, in the field of circuit board technology, traditional electroplating processes can achieve uniform plating of conductive copper layers on the surface of circuit boards and the inner walls of slots, but it is difficult to achieve the processing requirement of plating only the hole walls and not the hole opening face. In particular, since the hole walls in circuit boards are mostly vertical or inclined surfaces, this further increases the processing difficulty of accurately controlling the copper layer to cover only the hole walls and not the hole opening face.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] To overcome the above-mentioned defects, the present invention provides a processing method and a circuit board for a slotted hole with metallized hole wall and non-metallized hole end face. The processing method is simple and reasonable, and can accurately produce slotted holes with metallized hole wall and non-metallized hole end face, which can enable the circuit board to have a superior shielding effect and ensure the sensitivity and stability of the ultrasonic sensor.

[0006] The technical solution adopted by this invention to solve its technical problem is: a method for processing a non-metallized slot hole with a metallized hole wall and a non-metallized end face, comprising the following processing steps:

[0007] S1: A substrate is provided, and the substrate is sequentially processed by inner layer circuit fabrication, lamination, laser-cut slots, and outer layer circuit fabrication to obtain a working board with two sets of circuit structures and slot prototypes; wherein...

[0008] The two sets of circuit structures are arranged opposite each other along the thickness direction of the working board. Each set of circuit structures has an inner circuit layer and an outer circuit layer stacked on the outside of the inner circuit layer. The slot prototype penetrates through the two outer circuit layers. A connecting copper layer extending to the two outer circuit layers is provided on the inner wall of the slot prototype. The part of the connecting copper layer on the two outer circuit layers is the part to be removed.

[0009] In addition, according to the specific process adopted by the outer layer circuit, a protective tin layer is selectively arranged on the surface of the outer layer circuit layer and the connecting copper layer;

[0010] S2: When the protective tin layer is arranged on the surface of the outer layer circuit layer and the connecting copper layer, the following S3 is directly performed;

[0011] When the protective tin layer is not arranged on the surface of the outer layer circuit layer and the connecting copper layer, according to whether the outer layer circuit layer and the connecting copper layer are in electrical connection, the protective tin layer is selectively arranged on the surface of the outer layer circuit layer and the connecting copper layer by electroplating tin or chemical tin deposition process;

[0012] S3: The protective tin layer on the set area of the to-be-removed part is removed by a laser ablation process to form a processing window; and then the to-be-removed part is etched away based on the processing window;

[0013] S4: The protective tin layer is completely removed, that is, a slot hole with a hole wall metallization and a hole opening end surface non-metallization is obtained.

[0014] As a further improvement of the present application, in the above S1, when the outer layer circuit is made by subtractive process, the protective tin layer is not arranged on the surface of the outer layer circuit layer and the connecting copper layer; and when the outer layer circuit is made by mSAP process, the protective tin layer is arranged on the surface of the outer layer circuit layer and the connecting copper layer.

[0015] As a further improvement of the present application, in the above S1, when the protective tin layer is not arranged on the surface of the outer layer circuit layer and the connecting copper layer, a lead wire electrically connecting the outer layer circuit layer and the to-be-removed part located on the same side is selectively arranged between the two;

[0016] Correspondingly, in the above S2, when the lead wire is arranged, the protective tin layer is respectively arranged on the surface of the outer layer circuit layer, the connecting copper layer and the lead wire by electroplating tin process; and when the lead wire is not arranged, the protective tin layer is respectively deposited on the surface of the outer layer circuit layer and the connecting copper layer by chemical tin deposition process.

[0017] As a further improvement of the present application, in the above S3, the processing window is annular and surrounds the inner side periphery of the to-be-removed part, and the distance between the inner side of the processing window and the extension surface of the inner side of the to-be-removed part is not less than 20 μm.

[0018] As a further improvement of the present application, when the lead wire is provided, the protective tin layer on the set region of the part to be removed is removed by laser ablation process, and the protective tin layer provided on the surface of the lead wire is also ablated and removed.

[0019] As a further improvement of the present application, in the above S3, the processing parameters for etching the part to be removed are: the concentration of divalent copper ions in the etching solution is 150±15g / L, the concentration of monovalent chloride ions is 195±15g / L, the pH value of the etching solution is 8.45±0.35, the specific gravity is 1.21±0.02, the temperature is 50℃±5℃, the upper and lower spray pressures during etching are 1.5±0.5Kg / cm 2 , and the etching speed is 1.5±0.2m / min; through the above etching, the part to be removed is completely etched away, and the etched depth of the connecting copper layer provided on the inner wall of the slot hole outline is not greater than 5μm.

[0020] As a further improvement of the present application, in the above S1, the specific processing method of the workboard is:

[0021] S11: providing the substrate with a double-sided copper-clad plate structure, and sequentially performing drilling, through-hole plating, resin hole plugging, grinding, whole plate plating, film coating pretreatment, resist photosensitive film coating, exposure, development, etching and film removal processing on the substrate to obtain a first intermediate plate with two inner layer circuit layers; wherein the two inner layer circuit layers are oppositely arranged and electrically connected;

[0022] S12: sequentially stacking insulating build-up layers and copper foil build-up layers on the two inner layer circuit layers respectively, and then laminating and pressing to obtain a second intermediate plate; wherein the copper foil build-up layer is provided with a carrier copper layer and an ultra-thin copper layer detachably provided on the carrier copper layer, and the ultra-thin copper layer is arranged in close contact with the insulating build-up layer;

[0023] S13: removing the two carrier copper layers on the second intermediate plate, and then performing laser windowing and laser drilling to obtain the slot hole outline penetrating through the two ultra-thin copper layers;

[0024] S14: determining the specific process of outer layer circuit manufacturing, if the outer layer circuit manufacturing adopts subtractive process, then performing the operations in the following S15-S16; if the outer layer circuit manufacturing adopts mSAP process, then performing the operations in the following S17-S18;

[0025] S15: performing whole plate plating processing to realize plating of the connecting copper layer extending to the two ultra-thin copper layers on the inner wall of the slot hole outline, and plating of the copper layer in close contact with the part to be removed of the connecting copper layer on the two ultra-thin copper layers respectively; obtaining a third intermediate plate;

[0026] S16: After the third intermediate plate is sequentially subjected to film coating pretreatment, coating of an etching photosensitive film, exposure, development, etching and film removal processing, the outer layer circuit layer is manufactured, or the outer layer circuit layer and the lead wire are manufactured; the work plate is obtained;

[0027] S17: whole plate copper plating and flash plating processing are performed to form a super-thin copper layer A on the inner wall of the slot hole and the two super-thin copper layers respectively; a fourth intermediate plate is obtained;

[0028] S18: After the fourth intermediate plate is sequentially subjected to film coating pretreatment, coating of an etching photosensitive film, exposure, development, pattern copper plating, pattern tin plating, film removal, baking and flash etching processing, the outer layer circuit layer, the connecting copper layer and the protective tin layer respectively coated on the outer layer circuit layer and the connecting copper layer are manufactured; the work plate is obtained.

[0029] As a further improvement of the present application, in the above S15, the processing parameters of the whole plate plating are as follows: the concentration of monovalent chloride ions in the plating solution is 30-50 ppm, the concentration of divalent copper ions is 10-13 g / L, the concentration of sulfuric acid is 195-220 g / L, the temperature of the plating solution is 22-25°C, the cathode current density is not greater than 1.4 ASD, the plating time is 120-140 min, and the plating efficiency is 100%-110%; through the above whole plate plating processing, the copper thickness uniformity of the connecting copper layer and the copper plating layer is controlled within ±3 μm.

[0030] As a further improvement of the present application, in the above S17, the thickness of the super-thin copper layer A is 1-4 μm; in the above S18, the thickness of the protective tin layer is 4-6 μm.

[0031] The present application also provides a circuit board applied to an ultrasonic sensor, which comprises a plate main body manufactured by the processing method of the present application, i.e., the plate main body is provided with two groups of circuit structures and slot holes with hole wall metallization and hole opening end surface non-metallization characteristics.

[0032] The present application has the following advantages compared with the prior art: ① The present application can precisely manufacture slot holes with hole wall metallization and hole opening end surface non-metallization by the process innovation of "first plating a protective tin layer to protect the connecting copper layer on the hole wall, and then removing the connecting copper layer on the hole opening end surface by the combination of tin burning and alkaline etching", thereby realizing the superior shielding effect of the circuit board and ensuring the sensitivity and stability of the ultrasonic sensor. ② The slot hole processing method of the present application is simple, reasonable and easy to operate. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Flow chart of the method for processing the non-metallized groove of the hole wall metallized orifice end face of the hole according to the present application;

[0034] Figure 2 Cross-sectional structure schematic diagram of the substrate according to the embodiment 1 of the present application;

[0035] Figure 3 Cross-sectional structure schematic diagram of the first intermediate plate according to the embodiment 1 of the present application;

[0036] Figure 4 Cross-sectional structure schematic diagram of the second intermediate plate according to the embodiment 1 of the present application;

[0037] Figure 5 Cross-sectional structure schematic diagram of the second intermediate plate after the groove roughing is processed on the second intermediate plate according to the embodiment 1 of the present application;

[0038] Figure 6 Cross-sectional structure schematic diagram of the third intermediate plate according to the embodiment 1 of the present application;

[0039] Figure 7 Cross-sectional structure schematic diagram of the working plate according to the embodiment 1 of the present application;

[0040] Figure 8 Cross-sectional structure schematic diagram of the working plate after the protective tin layer is formed on the working plate according to the embodiment 1 of the present application;

[0041] Figure 9 Cross-sectional structure schematic diagram after the processing window is formed on the protective tin layer shown in the figure; Figure 8

[0042] Cross-sectional structure schematic diagram after the to-be-removed part is etched away based on the processing window shown in the figure; Figure 10 Figure 9 Cross-sectional structure schematic diagram of the plate body with the hole wall metallized orifice end face non-metallized groove obtained according to the embodiment 1 of the present application;

[0043] Figure 11 Cross-sectional structure schematic diagram of the working plate according to the embodiment 2 of the present application;

[0044] Figure 12 Cross-sectional structure schematic diagram of the working plate after the protective tin layer is formed on the working plate according to the embodiment 2 of the present application;

[0045] Figure 13 Cross-sectional structure schematic diagram after the processing window is formed on the protective tin layer shown in the figure;

[0046] Figure 14 Figure 13

[0047] ​​​Figure 15 For based on Figure 14 The diagram shows a cross-sectional structure after the part to be removed has been etched away through the processing window.

[0048] Figure 16 This is a schematic cross-sectional view of the fourth intermediate plate described in Embodiment 3 of the present invention;

[0049] Figure 17 This is a schematic cross-sectional view of the working board described in Embodiment 3 of the present invention;

[0050] Figure 18 In order to be in Figure 17 A schematic diagram of the cross-sectional structure after a processing window is formed on the protective tin layer;

[0051] Figure 19 For based on Figure 18 The diagram shows a cross-sectional structure after the part to be removed has been etched away through the processing window.

[0052] Referring to the accompanying drawings, the following explanations are provided:

[0053] 1. Substrate; 10. Insulating Intermediate Layer; 11. Copper Base Layer; 2. Slot Shape; 3. Inner Circuit Layer; 4. Outer Circuit Layer; 5. Protective Tin Layer; 50. Processing Window; 6. Connecting Copper Layer; 60. Part to be Removed; 7. Slot; 80. Insulating Addition Layer; 81. Carrier Copper Layer; 82. Ultra-thin Copper Layer; 9. Resin; 12. Connecting Copper Layer A; 13. Copper Plating Layer; 14. Connecting Copper Layer B; 15. Lead Wire; 16. Ultra-thin Copper Layer A; 17. Blind Via; B1. First Intermediate Board; B2. Second Intermediate Board; B3. Third Intermediate Board; B4. Fourth Intermediate Board; B5. Working Board; B6. Board Body. Detailed Implementation

[0054] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Example 1

[0055] Please see the appendix Figure 1 To be continued Figure 11 As shown, this embodiment 1 provides a method for processing a non-metallized groove hole with a metallized hole wall and a non-metallized end face, including the following processing steps:

[0056] S1: Provide a substrate 1, and after sequentially performing inner layer circuit fabrication, lamination, laser-cut slot holes and outer layer circuit fabrication on the substrate 1, a work board B5 with a slot hole prototype 2 and two sets of circuit structures is obtained.

[0057] Specifically, the processing method of the work board B5 described in this embodiment 1 is as follows:

[0058] S11: Provide a substrate 1, wherein the substrate 1 adopts a double-sided copper-clad laminate structure, i.e.: please refer to the appendix.Figure 2 As shown, the substrate 1 is provided with an insulating intermediate layer 10 and a copper-based layer 11 fixedly attached to the opposite surfaces of the insulating intermediate layer 10, the insulating intermediate layer 10 can be, but is not limited to, a prepreg, and the thickness of the insulating intermediate layer 10 and the copper-based layer 11 is determined according to the product design requirements, which is not limited in the present embodiment.

[0059] After the substrate 1 is sequentially cut, baked, drilled, through-hole electroplated, resin plugged, ground, whole-board electroplated, film-coated pretreated, resist photosensitive film-coated, exposed, developed, etched, and film-removed, a first intermediate plate B1 with two inner-layer circuit layers 3 is obtained; wherein,

[0060] ① The above-mentioned cutting and baking refer to cutting the substrate 1 into a set size, and then placing the substrate 1 in an oven for baking to eliminate the stress of the substrate 1, prevent the substrate 1 from warping, reduce the expansion and contraction of the substrate 1, and further improve the dimensional stability of the substrate 1. Further, the processing conditions of the above-mentioned baking can be preferably designed as follows: the temperature is 185-195°C, and the baking time is 2-4h.

[0061] ② The above-mentioned drilling refers to drilling alignment holes and through holes at predetermined positions of the substrate 1 by mechanical drilling and / or laser drilling.

[0062] Further, after the drilling process is completed, the inner wall of the through hole obtained is treated by plasma cleaning to remove the residue, and the substrate 1 is subjected to whole-board copper operation to achieve the overall thickening of the copper-based layer 11, and a seed layer is formed on the inner wall of the through hole, which provides the necessary implementation conditions for the following through-hole electroplating.

[0063] ③ The above-mentioned through-hole electroplating refers to through-hole electroplating in the through hole to form a connecting copper layer A12 on the seed layer; further, the two ends of the connecting copper layer A12 extend to the same level of the two thickened copper-based layers 11, respectively.

[0064] ④ The above-mentioned resin plugging, grinding, and whole-board electroplating refer to filling and compacting the resin 9 in the through hole by using a vacuum resin plugging machine, and after the resin 9 is solidified, the two ports of the through hole are ground by using a ceramic brush wheel to grind off the resin protruding from the two ports of the through hole; then, the ground board is subjected to whole-board electroplating to electroplate a copper layer on the copper-based layer 11 and the two ports of the through hole, and the copper layers are connected at the same level, which provides the necessary implementation conditions for the inner-layer circuit manufacturing in the subsequent process.

[0065] ⑤The aforementioned front treatment of the film and the anti-etch photosensitive film: after the plate after the aforementioned whole plate electroplating operation is roughened, cleaned and dried, the anti-etch photosensitive dry film is pasted on the two thickened copper base layers 11 by a vacuum film pasting machine. Understandably, the thickness of the anti-etch photosensitive dry film is determined according to the design requirements of the copper thickness of the inner layer circuit layer 3 of the product, and the embodiment does not limit the requirements.

[0066] ⑥The aforementioned exposure and development: according to the operation data and using an LDI exposure machine to expose part of the area of the anti-etch photosensitive dry film, and then using a developing solution (using a developing solution commonly used in the industry) to remove the unexposed area of the anti-etch photosensitive dry film.

[0067] ⑦The aforementioned etching and film removal: using an alkaline etching solution (using an etching solution commonly used in the industry) to etch the part of the two thickened copper base layers 11 exposed to the outside of the anti-etch photosensitive dry film, and then using a film removal solution (also using a film removal solution commonly used in the industry) to remove the anti-etch photosensitive dry film, that is, to obtain a first intermediate plate B1 with two inner layer circuit layers 3. For details, please refer to the accompanying drawings. Figure 3 Understandably, the inner layer circuit layer 3 is made by subtractive process.

[0068] Please continue to refer to the accompanying drawings Figure 3 The two inner layer circuit layers 3 are arranged opposite to each other along the thickness direction of the first intermediate plate B1. Of course, according to the design requirements of the product, the two inner layer circuit layers 3 can also be designed to be symmetrically arranged; and the two inner layer circuit layers 3 are electrically connected through the connecting copper layer A12.

[0069] In addition, after the first intermediate plate B1 is obtained, the inner layer circuit layer 3 is subjected to AOI optical detection to ensure the processing quality of the inner layer circuit layer 3.

[0070] S12: After the first intermediate plate B1 is pretreated (such as cleaning, drying, etc.) and browned, the insulating layer 80 and the copper foil layer are sequentially stacked on the two inner layer circuit layers 3, respectively, and then laminated and pressed to obtain a second intermediate plate B2. Please refer to the accompanying drawings. Figure 4

[0071] ​Further, the insulating build-up 80 can adopt a prepreg with a content of glue not less than 75%, and the thickness / number of layers of the insulating build-up 80 is determined according to the product design requirement, which is not limited in the embodiment. The copper foil build-up is provided with a carrier copper layer 81 and an ultrathin copper layer 82 detachably arranged on the carrier copper layer 81, the thickness of the carrier copper layer 81 can be preferably 18±2 μm, and the thickness of the ultrathin copper layer 82 can be preferably 3±0.2 μm, and the ultrathin copper layer 82 is arranged in close contact with the insulating build-up 80. It is explained that the ultrathin copper layer 82 is deposited on the carrier copper layer 81 by an electrodeposition processing technology, and before the electrodeposition processing, the carrier copper layer 81 is also treated with a chemical solution to ensure that the ultrathin copper layer 82 and the carrier copper layer 81 have a predetermined peeling force, which can achieve good separation; this is a conventional technical means in the field of circuit board, and therefore is not described in detail here.

[0072] Further, the preferred processing parameters of the laminating and pressing are as follows: the temperature rising rate is 3.5-4.5 ℃ / min, the pressing temperature is ≥220 ℃, and the maximum pressing pressure is ≥420 Psi. Through the above laminating and pressing mode, the overall structural stability of the second intermediate plate B2 can be ensured.

[0073] Further, after the second intermediate plate B2 is prepared, a positioning hole is also drilled at a predetermined position of the second intermediate plate B2 to facilitate the preparation of the slot hole sketch 2.

[0074] S13: first, the two carrier copper layers 81 on the second intermediate plate B2 are removed by mechanical peeling, then the predetermined positions on the two ultrathin copper layers 82 are laser windowed to prepare windows, and then the windows are laser drilled to prepare a slot hole sketch 2 penetrating through the two ultrathin copper layers 82; please refer to FIG. 6. Figure 5

[0075] Further, ① when laser windowing, the window A is also prepared at the predetermined position A on the two ultrathin copper layers 82, and then a plurality of blind holes 17 with the effective circuit area of the inner layer circuit layer 3 as the slot bottom are prepared based on the window A and by laser drilling. ② After laser windowing, the obtained window and window A need to be subjected to AOI optical detection to ensure the processing quality of the slot hole sketch 2 and the blind hole 17. ③ According to the product design requirement, the position layout of the slot hole sketch 2 avoids the effective circuit area of the inner layer circuit layer 3, that is, the local part of the slot hole sketch 2 falls on the ineffective area of the inner layer circuit layer 3, which can be combined with FIG. 6 and FIG. 7. Figure 4 Figure 5 ​​As shown; thus, when the above-mentioned laser drilling is performed to make the slot hole sketch 2, the insulating build-up layer 80 and the insulating intermediate layer 10 are partially removed, which does not adversely affect the effective circuit area of the inner circuit layer 3.

[0076] S14: The outer circuit layer is made by using subtractive process. As known from S11, the subtractive process includes the following steps in sequence: pre-treatment before film coating, coating of resist photosensitive film, exposure, development, etching and film removal.

[0077] S15: The second intermediate plate B2 with the slot hole sketch 2 and the blind hole 17 is subjected to whole-plate electroplating processing, so as to realize plating of the connecting copper layer 6 on the inner wall of the slot hole sketch 2, which extends to the two ultra-thin copper layers 82. The connecting copper layer 6 located on the two ultra-thin copper layers 82 and the ultra-thin copper layer 82 located below the connecting copper layer 6 together constitute a to-be-removed part 60. The connecting copper layer B14 is plated in the blind hole 17. The plated copper layer 13 is plated on the two ultra-thin copper layers 82 and connects the to-be-removed part 60 of the connecting copper layer 6 and the connecting copper layer B14, respectively. Further, the plated copper layer 13 is flush with the to-be-removed part 60. At this time, the third intermediate plate B3 is obtained. Please refer to FIG. 4. Figure 6 As shown.

[0078] Further, the whole-plate electroplating processing parameters in S15 are controlled as follows: the concentration of monovalent chloride ions (Cl -1 ) in the electroplating solution is 30-50 ppm, the concentration of divalent copper ions (Cu 2+ ) is 10-13 g / L, the concentration of sulfuric acid is 195-220 g / L, the temperature of the electroplating solution is 22-25℃, the cathode current density is not greater than 1.4 ASD, and the electroplating time is 120-140 min. The electroplating efficiency is 100%-110%. That is, the electroplating solution with “low concentration of divalent copper ions and high concentration of sulfuric acid” and the electroplating mode with “low cathode current density and long electroplating time” are used, so as to control the copper thickness uniformity of the connecting copper layer 6, the plated copper layer 13 and the connecting copper layer B14 to be within ±3 μm, respectively.

[0079] S16: After the third intermediate plate B3 is subjected to the following steps in sequence: pre-treatment before film coating, coating of resist photosensitive film, exposure, development, etching and film removal, the outer circuit layer 4 and the lead 15 are made on the composite copper layer composed of the plated copper layer 13 and the ultra-thin copper layer 82. The lead 15 is electrically connected between the outer circuit layer 4 (specifically, the effective circuit area of the outer circuit layer 4) and the to-be-removed part 60. At this time, the work plate B5 is obtained. Please refer to FIG. 5. Figure 7 As shown.

[0080] Further, ① the specific processing content of "pre-treatment before film covering, covering anti-etching photosensitive film, exposure, development, etching and film removal" in the present S16 can refer to the corresponding content described in the above S11, which will not be repeated here. ② In order to clearly show the figure, the following Figure 7 The copper plating layer 13 and the ultra-thin copper layer 82 are combined into one body, and the height of the connecting copper layer B14 is enlarged, as shown in the following Figure 6 It can be seen that the upper end of the connecting copper layer B14 is substantially located at the lower part of the outer layer circuit layer 4. ③ Two outer layer circuit layers 4 are respectively electrically connected to two inner layer circuit layers 3 through the connecting copper layer B14.

[0081] As can be seen from the above, the structure of the workboard B5 prepared in the present embodiment 1 is as follows: please continue to refer to the following Figure 7 As shown, it comprises two groups of circuit structures, a slot hole sketch 2 and a lead wire 15. Two groups of the circuit structures are oppositely arranged along the thickness direction of the workboard B5. Each group of the circuit structures is provided with an inner layer circuit layer 3 and an outer layer circuit layer 4 stacked outside the inner layer circuit layer 3. Two inner layer circuit layers 3 are electrically connected through the connecting copper layer A12. Two outer layer circuit layers 4 are respectively electrically connected to two inner layer circuit layers 3 through the connecting copper layer B14. The slot hole sketch 2 penetrates through two outer layer circuit layers 4 (specifically, it penetrates through the invalid area of two outer layer circuit layers 4). The connecting copper layer 6 is plated on the inner wall of the slot hole sketch 2 and extends to two outer layer circuit layers 4 (specifically, it extends to the invalid area of two outer layer circuit layers 4). The part of the connecting copper layer 6 on two outer layer circuit layers 4 is the to-be-removed part 60. In addition, the to-be-removed part 60 and the effective circuit area of the outer layer circuit layer 4 on the same side / layer are electrically connected through the lead wire 15.

[0082] S2: A protective tin layer 5 is plated on the surface of the outer layer circuit layer 4 (specifically, the surface of the effective circuit area of the outer layer circuit layer 4), the surface of the lead wire 15 and the surface of the connecting copper layer 6 by using the electroplating tin process; please refer to the following Figure 8 As can be understood, the core role of the protective tin layer 5 is to protect the effective circuit area of the outer layer circuit layer 4 from being attacked by alkaline etching in the later process. The role of the lead wire 15 is to make the outer layer circuit layer 4 and the connecting copper layer 6 conductive, so that the electroplating tin operation can be implemented.

[0083] Further, according to the product design requirements, the thickness of the protective tin layer 5 is optimally controlled to be 4-6 μm.

[0084] S3: first, the laser ablation process is located on the set area of the to be removed part 60 of the protective tin layer 5, and the protective tin layer 5 on the lead 15 is removed to form a processing window 50, which can be referred to in FIG. 4. Figure 9 Then, based on the processing window 50, the to-be-removed part 60 and the lead 15 are etched using an alkaline etching solution, which can be referred to in FIG. 5. Figure 10

[0085] Further, please continue to refer to FIG. 6. Figure 9 As shown in FIG. 6, the processing window 50 is annular and surrounds the inner side of the to-be-removed part 60, and the distance L between the inner side wall of the processing window 50 and the extension of the inner side wall of the to-be-removed part 60 is not less than 20μm. It can be understood that by optimizing the structure of the processing window 50 as described above, the to-be-removed part 60 and the lead 15 can be etched while the connecting copper layer 6 on the inner wall of the slot hole sketch 2 is not subjected to uncontrollable etching attack.

[0086] Further, the etching processing parameters / conditions in S3 are optimized, specifically: the concentration of divalent copper ions (Cu 2+ ) in the etching solution is 150±15g / L, the concentration of monovalent chloride ions (Cl -1 ) is 195±15g / L, the pH value of the etching solution is 8.45±0.35, the specific gravity is 1.21±0.02, the temperature is 50℃±5℃, the upper and lower spray pressures during etching are 1.5±0.5Kg / cm 2 , and the etching speed is 1.5±0.2m / min. By the above etching parameters / conditions, the to-be-removed part 60 and the lead 15 can be completely etched while ensuring that the etching depth of the connecting copper layer 6 on the inner wall of the slot hole sketch 2 is not greater than 5μm, which well meets the design requirements of PCB products.

[0087] S4: the protective tin layer 5 is completely removed using a tin removal solution (any commonly used tin removal solution can be used), and a slot hole 7 with a metalized hole wall and a non-metalized hole opening end surface is obtained, which can be referred to in FIG. 7. Figure 11

[0088] Further, after the protective tin layer 5 is removed, the outer circuit layer 4 is subjected to AOI optical detection to ensure the processing quality of the outer circuit layer 4.

[0089] ​​In addition, for the following description, the plate with the slot hole 7 and the two sets of line structures prepared in S4 is defined as a plate body B6. The plate body B6 includes the two sets of line structures and the slot hole 7. The two sets of line structures are oppositely arranged along the thickness direction of the plate body B6. Each set of the line structures is provided with an inner line layer 3 and an outer line layer 4 stacked outside the inner line layer 3. The two inner line layers 3 are electrically connected by the connecting copper layer A12. The two outer line layers 4 are respectively electrically connected to the two inner line layers 3 by the connecting copper layer B14. The slot hole 7 penetrates through the two outer line layers 4 (specifically, the invalid regions of the two outer line layers 4). The inner wall of the slot hole 7 is plated with the connecting copper layer 6. The opening end surface of the slot hole 7 is not provided with the connecting copper layer 6, that is, the hole wall of the slot hole 7 is in a metallized state, and the opening end surface is in a non-metallized state.

[0090] As can be seen from the above, compared with the prior art, the slot hole processing method provided in Embodiment 1 has the following advantages: ① By process innovation, the slot hole processing method provided in Embodiment 1 adopts “first plating a protective tin layer to protect the connecting copper layer on the hole wall, and then removing the connecting copper layer on the opening end surface by combining tin burning and alkaline etching”, which can accurately prepare a slot hole with a metallized hole wall and a non-metallized opening end surface, thereby enabling the line board to have superior shielding effect and ensuring the sensitivity and stability of the ultrasonic sensor. ② The slot hole processing method provided in Embodiment 1 is simple, reasonable, and easy to operate. Embodiment 2

[0091] Embodiment 2 also provides a slot hole processing method with a metallized hole wall and a non-metallized opening end surface. Compared with Embodiment 1, the slot hole processing method provided in Embodiment 2 has the following difference points: difference point ①, when S1 is implemented, the surface of the outer line layer 4 and the connecting copper layer 6 prepared in Embodiment 2 is not provided with the protective tin layer 5, and the outer line layer 4 and the connecting copper layer 6 are not electrically connected, that is, Embodiment 2 does not configure the lead 15; difference point ②, when S2 is implemented, the protective tin layer 5 is deposited on the surface of the outer line layer 4 and the surface of the connecting copper layer 6 by using a chemical tin deposition process.

[0092] Specifically, regarding the aforementioned difference ①, in this embodiment 2, after the third intermediate board B3 is fabricated according to S11-S15 provided in embodiment 1, the third intermediate board B3 is sequentially subjected to pre-coating treatment, coating with photosensitive resist film, exposure, development, etching, and film removal (the specific processing content of the above steps can be found in the corresponding content described in S11 above), so as to achieve the fabrication of an outer circuit layer 4 on the composite copper layer composed of the copper plating layer 13 and the ultra-thin copper layer 82, and the outer circuit layer 4 is not electrically connected to the connecting copper layer 6; at that time, the working board B5 is obtained; for details, please refer to the appendix. Figure 12 As shown.

[0093] Furthermore, in this embodiment 2, for clarity of illustration, the attached diagram is provided. Figure 12 The copper plating layer 13 and the ultra-thin copper layer 82 are also integrated into one unit, and the height of the connecting copper layer B14 is increased. The upper end of the connecting copper layer B14 is actually located below the outer circuit layer 4. In addition, the two outer circuit layers 4 are also electrically connected to the two inner circuit layers 3 respectively through the connecting copper layer B14.

[0094] Understandably, the structure of the work board B5 obtained in this embodiment 2 is as follows: Please refer to the appendix. Figure 12 As shown, the circuit includes two sets of circuit structures and a slot prototype 2. The two sets of circuit structures are arranged opposite each other along the thickness direction of the working board B5. Each set of circuit structures has an inner circuit layer 3 and an outer circuit layer 4 stacked on the outside of the inner circuit layer 3. The two inner circuit layers 3 are electrically connected through the connecting copper layer A12, and the two outer circuit layers 4 are respectively electrically connected to the two inner circuit layers 3 through the connecting copper layer B14. The slot prototype 2 penetrates through the two outer circuit layers 4 (specifically, it penetrates through the ineffective area of ​​the two outer circuit layers 4). The inner wall of the slot prototype 2 is plated with a connecting copper layer 6 extending to the two outer circuit layers 4 (specifically, it extends to the ineffective area of ​​the two outer circuit layers 4), and the part of the connecting copper layer 6 on the two outer circuit layers 4 is the part to be removed 60.

[0095] Regarding the aforementioned difference ②, after the working board B5 is obtained, in this embodiment 2, a protective tin layer 5 with a thickness of 1.5μm ± 0.2μm is deposited on the surface of the outer circuit layer 4 and the surface of the connecting copper layer 6 using a chemical tin deposition process. See Appendix [link to Appendix]. Figure 13As shown. Understandably, since the thickness of the protective tin layer 5 prepared in this embodiment 2 is thinner, and the lead wire 15 is not configured, this embodiment 2 greatly reduces the processing difficulty and processing cost of the tin burning operation in the subsequent process, that is, this embodiment 2 can realize efficient and low-cost ablation and removal of the protective tin layer 5 on the set area of the to-be-removed part 60 to form the processing window 50. Please refer to the following figure for details. Figure 14 In addition, as in the above embodiment 1, in this embodiment 2, the distance between the inner side wall of the processing window 50 and the extension of the inner side wall of the to-be-removed part 60 is also designed to be not less than 20μm. In addition, the following figure shows the case of etching away the to-be-removed part 60 based on the processing window 50. Understandably, this embodiment 2 not only can ensure that the to-be-removed part 60 is completely etched away, and ensure that the etching depth of the connection copper layer 6 arranged on the inner wall of the slot hole sketch 2 is not more than 5μm, but also effectively improves the etching efficiency due to the absence of the lead wire 15. Figure 15

[0096] Description: In the process of processing the slot hole in this embodiment 2, in addition to the above two distinguishing points, other aspects such as the manufacturing method of the third intermediate plate B3, the manufacturing method of the outer layer circuit layer 4, the laser tin burning method, and the tin stripping method are the same as / similar to those of embodiment 1; therefore, the structure of the plate A with the slot hole 7 and two groups of circuit structures prepared after completing the tin stripping in this embodiment 2 is the same as that of the plate main body B6 obtained in embodiment 1, and thus is not described here. Please refer to the following figure for details. Figure 11

[0097] As can be seen from the above, compared with embodiment 1, the slot hole processing method provided by this embodiment 2 not only realizes the accurate preparation of the slot hole with the metalized hole wall and the non-metalized hole opening end face, but also significantly reduces the processing difficulty and processing cost and improves the processing efficiency. Embodiment 3

[0098] This embodiment 3 also provides a processing method of a slot hole with a metalized hole wall and a non-metalized hole opening end face, and compared with embodiment 1, the slot hole processing method provided by this embodiment 3 has the following distinguishing points: distinguishing point ①, when S1 is implemented, the outer layer circuit manufacturing process used in this embodiment 3 is different from that of embodiment 1. Distinguishing point ②, when S3 is implemented, the outer layer circuit layer 4 needs to be coated and protected before etching the to-be-removed part 60.

[0099] Specifically, regarding the above distinguishing point ①, after the second intermediate plate B2 with the slot hole sketch 2 and the blind hole 17 is prepared according to S11-S13 provided in the above embodiment 1, an mSAP process is used to perform the outer layer circuit manufacturing in the subsequent process.

[0100] ​​Further, the method for manufacturing the outer circuit layer of the second intermediate plate B2 with the slot hole sketch 2 and the blind hole 17 by the mSAP process in this embodiment 3 is as follows:

[0101] S17: sequentially performing whole-plate copper deposition and flash plating processing on the second intermediate plate B2 with the slot hole sketch 2 and the blind hole 17, so as to form a super-thin copper layer A16 with a thickness of 1-4 μm on the inner wall of the slot hole sketch 2, the inner wall of the blind hole 17 and the two super-thin copper layers 82 respectively, thereby obtaining a fourth intermediate plate B4; please refer to FIG. 4. Figure 16

[0102] It can be understood that the super-thin copper layer A16 respectively located on the inner wall of the slot hole sketch 2, the inner wall of the blind hole 17 and the super-thin copper layer 82 is smoothly connected.

[0103] S18: after sequentially performing film-coating pretreatment, anti-plating photosensitive film coating, exposure, development, pattern copper plating, pattern tin plating, film removal, baking and flash etching processing on the obtained fourth intermediate plate B4, the outer circuit layer 4, the connecting copper layer 6 and the protective tin layer 5 respectively coated on the outer circuit layer 4 and the connecting copper layer 6 are manufactured; at this time, the working plate B5 is obtained, please refer to FIG. 5. Figure 17

[0104] ① The above-mentioned film-coating pretreatment and anti-plating photosensitive film coating refer to that after performing roughening, cleaning and drying treatment on the obtained fourth intermediate plate B4, the anti-plating photosensitive dry film is pasted on the opposite two surfaces of the fourth intermediate plate B4 by a vacuum film pasting machine. It can be understood that the thickness of the anti-plating photosensitive dry film is determined according to the copper thickness design requirement of the product on the outer circuit layer 4, and this embodiment does not have a limitation requirement.

[0105] ② The above-mentioned exposure and development refer to that according to the working data and by using an LDI exposure machine, the anti-plating photosensitive dry film is exposed in some areas, and then by using a developing solution, the areas of the anti-plating photosensitive dry film which are not exposed are removed.

[0106] ③ The above-mentioned pattern copper plating refers to that by using a through-hole plating process, a thickened copper plating layer is plated on the inner wall of the slot hole sketch 2, in the blind hole 17 and on the exposed area of the super-thin copper layer A16 which are not covered by the anti-plating photosensitive dry film, so as to form the sketch of the outer circuit layer, the sketch of the connecting copper layer and the connecting copper layer B14 which electrically connects the sketch of the outer circuit layer and the inner circuit layer 3.

[0107] ④ The above-mentioned pattern tin plating refers to that a protective tin layer 5 with a thickness of 4-6 μm is plated on the sketch of the outer circuit layer and the sketch of the connecting copper layer.

[0108] ​​⑤ The above-mentioned film removal, baking, and flash etching refer to the process of removing the photosensitive dry film using a strong alkaline solution, drying the entire board, and then performing flash etching to etch away the ultra-thin copper layer A16 and the ultra-thin copper layer 82 that are not covered by the protective tin layer 5, thereby forming the outer circuit layer 4 and the connecting copper layer 6. It is understood that the copper thickness of the portion 60 to be removed in the connecting copper layer 6 and the copper thickness of the outer circuit layer 4 are respectively "the sum of the copper thickness of the ultra-thin copper layer 82, the copper thickness of the ultra-thin copper layer A16, and the copper thickness of the thickened copper plating layer". The copper thickness of the connecting copper layer 6 located on the inner wall of the slot prototype 2 is equal to the sum of the copper thickness of the ultra-thin copper layer A16 and the copper thickness of the thickened copper plating layer.

[0109] As can be seen from the above, the structure of the work board B5 obtained in this embodiment 3 is as follows: Please refer to the appendix for further details. Figure 17 As shown, the circuit includes two sets of circuit structures and a slot prototype 2. The two sets of circuit structures are arranged opposite each other along the thickness direction of the working board B5. Each set of circuit structures has an inner circuit layer 3 and an outer circuit layer 4 stacked on the outside of the inner circuit layer 3. The two inner circuit layers 3 are electrically connected through the connecting copper layer A12, and the two outer circuit layers 4 are respectively electrically connected to the two inner circuit layers 3 through the connecting copper layer B14. The slot prototype 2 penetrates through the two outer circuit layers 4 (specifically, through the ineffective area of ​​the two outer circuit layers 4). The inner wall of the slot prototype 2 is plated with a connecting copper layer 6 extending to the two outer circuit layers 4 (specifically, extending to the ineffective area of ​​the two outer circuit layers 4), and the part of the connecting copper layer 6 on the two outer circuit layers 4 is the part to be removed 60. In addition, the protective tin layer 5 is provided on the two outer circuit layers 4 and the connecting copper layer 6 respectively.

[0110] Regarding the aforementioned difference ②, based on the specific structure of the work board B5 obtained in this embodiment 3, this embodiment 3 first uses the same laser ablation method as in embodiment 1 to remove the protective tin layer 5 located on the designated area of ​​the part to be removed 60, so as to form the processing window 50. See the attached document for details. Figure 18 As shown; and in this embodiment 3, the distance between the inner sidewall of the processing window 50 and the extended surface of the inner sidewall of the part to be removed 60 is also designed to be not less than 20μm; then, in this embodiment 3, the obtained work board B5 is subjected to pre-coating treatment (cleaning, drying), coating with photoresist film, exposure and development operations, so that the outer circuit layer 4 is protected by coating, while the processing window 50 is exposed outside the photoresist film; then, based on the processing window 50, the part to be removed 60 is completely etched away, while controlling the etching depth of the connecting copper layer 6 on the inner wall of the slot prototype 2 to be no more than 5μm, see Appendix Figure 19The last step is to remove the film and tin, and the plate B with the slot hole 7 and two groups of the line structure is obtained.

[0111] Description: In the slot hole processing of this embodiment 3, in addition to the above two differences, other aspects such as the second intermediate plate B2 with the slot hole roughness 2 and the blind hole 17, the laser tin burning method, the tin stripping method, etc. are the same / similar to those of embodiment 1; therefore, the structure of the plate B obtained in this embodiment 3 can be the same as that of the plate main body B6 obtained in embodiment 1, and thus is not described here in detail, and can be referred to in the drawings of embodiment 1. Figure 11

[0112] As can be seen from the above, compared with embodiment 1, the slot hole processing method provided in this embodiment 3 can not only accurately produce a slot hole with a metalized hole wall and a non-metalized hole opening end face, but also has better reliability of the plate B due to the combination of the process of “firstly covering the outer line layer 4 with a film protection, and then etching the to-be-removed part 60”. Embodiment 4

[0113] This embodiment 4 provides a line plate applied in an ultrasonic sensor, which comprises a plate main body, and the plate main body is made of the slot hole processing method with a metalized hole wall and a non-metalized hole opening end face provided in the above embodiment 1, or embodiment 2, or embodiment 3, that is, the plate main body is provided with two groups of line structures and a slot hole 7 with the characteristics of a metalized hole wall and a non-metalized hole opening end face; and can be referred to in the drawings of embodiment 1. Figure 11

[0114] As can be seen from the above, the line plate obtained in this embodiment 4 has superior shielding effect, which ensures the sensitivity and stability of the ultrasonic sensor.

[0115] Finally, the prefixes “first”, “second”, “third” and the like (such as first intermediate plate, second intermediate plate, third intermediate plate, etc.) of the component names in the patent specification, and the suffixes “A”, “B”, “C” and the like (such as connecting copper layer A, connecting copper layer B, etc.) of the component names are only for clear description, and are not used to limit the scope of the patent.

[0116] ​​In the foregoing description, numerous specific details are set forth to provide a thorough understanding of the present application. However, there can be cases in which certain implementations of the present application are practicable even though some of the specific details are not disclosed. Therefore, the scope of the present application is defined by the appended claims rather than the foregoing description of the preferred embodiments. It will be apparent to those skilled in the art that many modifications, both to the methods and to the apparatus, can be practiced with the present application without departing from the spirit and the essential characteristics of the present application. Thus, the scope of the present application should be limited only by the appended claims and equivalents thereof.

Claims

1. A method for processing a non-metallized slot at the end face of a hole with a metallized hole wall, characterized in that: The processing steps include the following: S1: Provide a substrate (1), and sequentially perform inner layer circuit fabrication, lamination, laser-cut slot holes, and outer layer circuit fabrication on the substrate (1) to obtain a working board with two sets of circuit structures and slot hole prototypes (2); wherein, The two sets of circuit structures are arranged opposite each other along the thickness direction of the working board. Each set of circuit structures is provided with an inner circuit layer (3) and an outer circuit layer (4) stacked on the outside of the inner circuit layer (3). The slot prototype (2) penetrates through the two outer circuit layers (4). A connecting copper layer (6) extending to the two outer circuit layers (4) is provided on the inner wall of the slot prototype (2). The part of the connecting copper layer (6) located on the two outer circuit layers (4) is the part to be removed (60). In addition, depending on the specific process used in the fabrication of the outer circuit, a protective tin layer (5) is selectively provided on the surface of the outer circuit layer (4) and the connecting copper layer (6). S2: When the protective tin layer (5) is provided on the surface of the outer circuit layer (4) and the connecting copper layer (6), the operation in S3 below is performed directly. When the protective tin layer (5) is not provided on the surface of the outer circuit layer (4) and the connecting copper layer (6), the protective tin layer (5) is selectively provided on the surface of the outer circuit layer (4) and the connecting copper layer (6) by electroplating tin or chemical tin immersion process, depending on whether the outer circuit layer (4) and the connecting copper layer (6) are electrically connected. S3: The protective tin layer (5) on the designated area of ​​the part to be removed (60) is removed by laser ablation process to form a processing window (50); then the part to be removed (60) is etched away based on the processing window (50); S4: Completely remove the protective tin layer (5) to obtain a slot (7) with metallized hole walls and non-metallized hole opening end face.

2. The method for processing a non-metallized slot at the end face of a metallized hole with a metallized hole wall according to claim 1, characterized in that: In the above S1, when the outer circuit is fabricated using a subtractive process, the protective tin layer (5) is not provided on the surface of the outer circuit layer (4) and the connecting copper layer (6); while when the outer circuit is fabricated using the mSAP process, the protective tin layer (5) is provided on the surface of the outer circuit layer (4) and the connecting copper layer (6).

3. The method for processing a non-metallized slot at the end face of a metallized hole with a metallized hole wall according to claim 2, characterized in that: In the above S1, when the protective tin layer (5) is not provided on the surface of the outer circuit layer (4) and the connecting copper layer (6), a lead wire that electrically connects the two is selectively provided between the outer circuit layer (4) and the part to be removed (60) located on the same side. Accordingly, in the above S2, when the lead is provided, the protective tin layer (5) is plated on the surface of the outer circuit layer (4), the connecting copper layer (6) and the lead using an electroplating tin process; while when the lead is not provided, the protective tin layer (5) is deposited on the surface of the outer circuit layer (4) and the connecting copper layer (6) using a chemical tin deposition process.

4. The method for processing a non-metallized slot at the end face of a metallized hole with a metallized hole wall according to claim 1, characterized in that: In the above S3, the processing window (50) is ring-shaped and surrounds the inner periphery of the part to be removed (60), and the distance between the inner side of the processing window (50) and the extended surface of the inner side of the part to be removed (60) is not less than 20μm.

5. The method for processing a non-metallized slot at the end face of a metallized hole with a metallized hole wall according to claim 3, characterized in that: When the lead is provided, the protective tin layer (5) on the designated area of ​​the part to be removed (60) is removed by laser ablation process, and the protective tin layer (5) provided on the surface of the lead is also ablated and removed.

6. The method for processing a non-metallized slot at the end face of a metallized hole wall according to claim 1, characterized in that: In S3 above, the etching parameters for the part to be removed (60) are as follows: the concentration of divalent copper ions in the etching solution is 150±15g / L, the concentration of monovalent chloride ions is 195±15g / L, the pH value of the etching solution is 8.45±0.35, the specific gravity is 1.21±0.02, the temperature is 50℃±5℃, and the upper and lower spray pressures during etching are 1.5±0.5Kg / cm². 2 The etching rate is 1.5 ± 0.2 m / min; Through the above etching, the part to be removed (60) is completely etched away, while the etching depth of the connecting copper layer (6) on the inner wall of the slot prototype (2) is not greater than 5μm.

7. The method for processing a non-metallized slot at the end face of a metallized hole with a metallized hole wall according to claim 3, characterized in that: In S1 above, the specific processing method of the work plate is as follows: S11: The substrate (1) with a double-sided copper clad laminate structure is provided. The substrate (1) is subjected to drilling, through-hole electroplating, resin plugging, grinding, whole-board electroplating, pre-coating treatment, coating with photosensitive anti-corrosion film, exposure, development, etching and film removal processes in sequence to obtain a first intermediate board having two inner circuit layers (3); wherein the two inner circuit layers (3) are disposed opposite to each other and electrically connected. S12: An insulating layer (80) and a copper foil layer are stacked sequentially on the two inner circuit layers (3), and then laminated to obtain a second intermediate board; wherein, the copper foil layer is provided with a carrier copper layer (81) and an ultra-thin copper layer (82) that is detachably disposed on the carrier copper layer (81), and the ultra-thin copper layer (82) is bonded to the insulating layer (80); S13: After removing the two carrier copper layers (81) on the second intermediate plate, laser windowing and laser drilling are performed to obtain the slot prototype (2) that penetrates the two ultra-thin copper layers (82). S14: Determine the specific process for fabricating the outer layer circuit. If the outer layer circuit is fabricated using a subtractive process, then perform the operations in S15 to S16 below; if the outer layer circuit is fabricated using an mSAP process, then perform the operations in S17 to S18 below. S15: Perform whole-board electroplating to plate the connecting copper layer (6) extending to the two ultra-thin copper layers (82) on the inner wall of the slot prototype (2), and plate the copper plating layer flush with the part (60) to be removed of the connecting copper layer (6) on the two ultra-thin copper layers (82); to obtain the third intermediate board; S16: After performing pre-coating treatment, coating with photosensitive film, exposure, development, etching and film removal on the third intermediate board in sequence, the outer circuit layer (4) is produced, or the outer circuit layer (4) and the lead wire are produced; the working board is obtained. S17: Perform full-board copper plating and flash plating to form ultra-thin copper layers A on the inner wall of the slot prototype (2) and the two ultra-thin copper layers (82) respectively; to obtain the fourth intermediate board; S18: After performing pre-coating treatment, coating with photosensitive anti-plating film, exposure, development, patterned copper plating, patterned tin plating, film removal, baking and flash etching on the fourth intermediate board, the outer circuit layer (4), the connecting copper layer (6), and the protective tin layer (5) respectively coated on the outer circuit layer (4) and the connecting copper layer (6) are produced; the working board is obtained.

8. The method for processing a non-metallized slot at the end face of a metallized hole with a metallized hole wall according to claim 7, characterized in that: In the above S15, the processing parameters for the whole plate electroplating are as follows: the concentration of monovalent chloride ions in the electroplating solution is 30-50 ppm, the concentration of divalent copper ions is 10-13 g / L, the concentration of sulfuric acid is 195-220 g / L, the temperature of the electroplating solution is 22-25℃, the cathode current density is not greater than 1.4 ASD, the electroplating time is 120-140 min, and the electroplating efficiency is 100%-110%. Through the above whole plate electroplating process, the copper thickness uniformity of the connecting copper layer (6) and the copper plating layer is controlled within ±3 μm.

9. The method for processing a non-metallized slot at the end face of a metallized hole with a metallized hole wall according to claim 7, characterized in that: In S17 above, the thickness of the ultrathin copper layer A is 1 to 4 μm; in S18 above, the thickness of the protective tin layer (5) is 4 to 6 μm.

10. A circuit board used in an ultrasonic sensor, characterized in that: The board body is made by the processing method of the slotted hole with metallized hole wall and non-metallized hole end face as described in any one of claims 1-9. That is, the board body is provided with two sets of circuit structures and slotted holes with metallized hole wall and non-metallized hole end face characteristics (7).

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